why have i received two account verification codes?

When accessing my hotmail account the process was interrupted to ask me to get a code number. My telephone number was already there so I clicked to get the code sent by a phone call. I immediately got a call with a four digit number but as soon as I put the phone down I got another call with a second, different four digit number. I am hesitant to use either of these as I don't know if they are real or attempts at hacking. What should I do? Please answer in very simple terms as I'm not a computer expert and haven't understood most of what I've read about this subject on the forum.